Long time lurker, short time poster.
This has been on my mind for a while.  About 5 years ago, I read through a homebrew campaign here on the boards that I loved, but like many games on these boards seem to do, it faded and disappeared.  Now I'm getting to a point in my life where I'm thinking of building a campaign world for future games, and I really want to adapt that homebrew world.  I have my own changes I want to make to it, but I feel bad because it feels like I'm taking advantage of someone else's work.  I'm not going to be running a podcast or stream something, or even write a full book where I try and profit off of this pre-created world, so there isn't any ethical dilemma, but still...I feel bad.  
Maybe it's because it's not a big publicized setting like Golarion put out by a company.  From the campaign notes I read, this world was crafted with lots of love and passion for the game.  The premise was really exciting and there were lots of fun places for the adventure to go
Not sure if this is the right place for it, but should I feel bad?  Or am I just overthinking things?
Anyone else ever adapted someone else's campaign?  Not just a setting like Paizo or WotC puts out, but something you or a friend played in or heard about?
TL,DR: I'm using someone else's campaign as a template so I don't have to write everything up and I feel guilty for some reason